A one-alarm fire started by a portable heater caused $70,000 worth of damage to a storage shed at a Tridelphia Road home Sunday night, Howard fire and rescue officials said.

Firefighters from the West Friendship, Lisbon, Ellicott City and Bethany stations put out the 10:59 p.m. blaze in about an hour.

The detached storage structure, in the 11700 block of Triadelphia Road, was being coverted to a wood shop, said Lt. Michael Gearhart, a fire and rescue spokesman.

The building sustained $20,000 in damage and tools and contents valued at about $50,000 were damaged or destroyed, Lt. Gearhart said.